1. Field of the Invention
The present invention relates to a positive temperature coefficient (PTC) rod assembly and a PTC heater using the same, and more particularly, to a PTC rod assembly in which PTC elements and an electrode terminal to which an insulator is attached are retained in a channel-shaped rod cover having an open side so as to be exposed to the outside, and a heat-radiating fin is in direct contact with one surface of the rod cover so as to conduct heat, and another heat-radiating fin is in direct contact with one surface of the insulator attached to an outer surface of the electrode terminal so as to conduct heat, thereby minimizing an empty space in an inner space of the rod cover, increasing heat transfer efficiency, and being easily manufactured due to a simple structure and reduction in the number of parts, and a PTC heater in which a heat-radiating fin contacting a rod cover and another heat-radiating fin contacting an insulator of an electrode terminal are contacted and coupled with opposite surfaces of the PTC rod assembly, thereby increasing heat transfer efficiency with respect to the heat-radiating fins, and improving entire energy efficiency and performance.
2. Description of Related Art
A vehicle is equipped with an air conditioning system for selectively supplying cold and warm air to the inside thereof. In the summer season, an air conditioner is actuated to supply the cold air. In the winter season, a heater is actuated to supply the warm air.
In general, the heater is based on a heating system in which coolant heated by circulating through an engine exchanges heat with air introduced by a fan, so that warmed air is supplied to the inside of the vehicle. This heating system has high energy efficiency because it uses the heat generated from the engine.
However, in the winter season, it takes some time until the engine is heated after starting. Thus, after starting, heating is not immediately available. As such, for the heating, the engine often idles for a predetermined time prior to moving the vehicle until the engine is heated to raise the temperature of the coolant. This idling of the engine causes energy waste and environmental pollution.
In order to prevent this problem, a use has been made of a method of heating the interior of the vehicle using a separate pre-heater for a predetermined time while the engine is being warmed up. A conventional heater using a heating coil effectively performs the heating due to a high quantity of heat, but its parts are frequently repaired and exchanged due to a short lifetime of the heating coil.
Thus, a heater using a positive temperature coefficient (PTC) element has recently been developed. This PTC heater has low fire danger, and can guarantee semi-permanent use due to a long lifetime.
As illustrated in FIG. 1, a PTC pre-heater includes PTC rod assemblies 10, each of which has a PTC element, heat-radiating fin assemblies 20, which are disposed in parallel on opposite sides of the respective PTC rod assemblies 10 in pairs, and cathode terminals 30 disposed in parallel between the heat-radiating fin assemblies 20. The PTC pre-heater further includes frames 40 and 50 mounted on opposite outer sides of a coupling block in which the PTC rod assemblies 10, heat-radiating fin assemblies 20 and cathode terminals 30 are coupled to each other, and housings 60 and 70 coupled to opposite longitudinal ends of a coupling block in which the PTC rod assemblies 10, heat-radiating fin assemblies 20, cathode terminals 30 and the frames 40 and 50 are coupled to each other.
As illustrated in FIGS. 2 and 3, a lower rod cover 11 has a channel shape, and serves as a kind of a container. An insulator 12 is disposed in the bottom of the lower rod cover 11 so as to prevent a short circuit. The insulator 12 is made of a material having properties of a nonconductor such as nylon and good thermal conductivity.
An anode terminal 17 is fixedly coupled on the insulator 12 in a longitudinal direction, and is made of a metal such as carbon steel or aluminum. PTC elements 18 are placed on the anode terminal 17, are fixedly coupled to the insulator 12, and are powered to generate heat. Further, an upper rod cover 19 is placed on the PTC elements 18, and is coupled with the lower rod cover 11. Electric current flows to each cathode terminal 30 through the upper and lower rod covers 11 and 19.
However, a PTC rod assembly having this structure has problems in that many parts are assembled because the insulator 12 are separately required, in that a shape of each part is complicated, making an assembling process difficult, and in that the thickness thereof is increased. Thus, an insulating effect is increased to deteriorate heat transfer efficiency. Further, the lower rod cover 11 is not in direct contact with the PTC elements 18 from the structural point of view, and air exists between the parts, so that the heat transfer efficiency of the PTC elements is lowered. Due to expansion of internal air caused by heating, the parts are separated from each other, so that the air leaks out when the pre-heater is initially driven, thereby causing noise and lowering performance.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.